HGT of TEs in humans growing in number

The term "junk DNA" was first coined in the 1970s to refer to the vast majority of the human genome that does not code for proteins. This includes transposable elements (TEs), which are segments of DNA that can move around the genome. TEs were originally thought to be useless. Neo-Darwinism, also known as the Modern Synthesis, is a theory of evolution that combines Darwin's theory of natural selection with Mendelian genetics. It states that evolution occurs through the gradual accumulation of beneficial mutations in a population over time.

The Modern Synthesis explicitly considered TEs as Junk DNA. Early proponents of the theory argued that TEs were not under the control of natural selection and therefore did not contribute to evolution.


The article "Widespread of horizontal gene transfer events in eukaryotes" by Zhang et al. (2022) examines the prevalence of horizontal gene transfer (HGT) in eukaryotic genomes. HGT is the transfer of genetic material (Transposons,TE) between organisms that are not closely related, and it is a major driver of genome evolution in prokaryotes. However, HGT events in eukaryotes were thought to be rare, particularly in mammals.

The authors of this study used a computational approach to identify HGT regions in the genomes of 13 model eukaryotes. They found that upwards of 358 non-redundant HGTs per species were present in the genomes of these 13 model organisms. Most of these HGTs were previously unknown. The authors also found that the majority of the 824 eukaryotes with full length genome sequences also contain HGTs. These HGTs have transformed their host genomes with thousands of copies of TEs and have impacted hundreds, even thousands of genes.

These findings suggest that HGT is more widespread in eukaryotes than previously thought. The authors propose that HGT may have played a significant role in the evolution of eukaryotic genomes, especially in the acquisition of new genes and the adaptation to new environments.

The authors also identified several potential routes of HGT in eukaryotes. One route involves blood sucking parasites, such as ticks and mosquitoes. These parasites can transmit genes from their hosts to other organisms. Another route involves intracellular pathogens, such as bacteria and viruses. These pathogens can also transfer genes to their hosts.

The findings of this study have important implications for our understanding of eukaryotic genome evolution. They suggest that HGT is a more significant force than previously thought, and that it has played a role in the acquisition of new genes and the adaptation to new environments. This study also provides new insights into the mechanisms of HGT in eukaryotes.

Here are some of the key takeaways from the article:

  • HGT is more widespread in eukaryotes than previously thought.

  • HGT may have played a significant role in the evolution of eukaryotic genomes.

  • There are several potential routes of HGT in eukaryotes.

  • Blood sucking parasites, intracellular pathogens, and viruses can all transfer genes between organisms.

  • The findings of this study have important implications for our understanding of eukaryotic genome evolution.

Horizontal gene transfer (HGT) of transposable elements (TEs) can make the concept of common ancestry problematic. TEs are mobile genetic elements that can move from one genome to another. This can happen through a variety of mechanisms, such as conjugation, transformation, and transduction.

When TEs are transferred between species, it can make it difficult to determine which species inherited the TE from a common ancestor and which species acquired it through HGT. This is because TEs can be highly similar between species, even if they were not inherited from a common ancestor.

For example, the human genome contains about 45% TEs. Many of the TEs in the human genome are also found in the genomes of bacteria. This suggests that these TEs were acquired by humans through HGT.

The presence of TEs that have been transferred through HGT can make it difficult to reconstruct the evolutionary history of a species. This is because it can be difficult to distinguish between TEs that were inherited from a common ancestor and TEs that were acquired through HGT. The more studies that are done the more HGT of TEs are found.

Article Snippets

HGT events in eukaryotes are considered as rare, particularly in mammals

we report the identification of HGT regions (HGTs) in 13 model eukaryotes by comparing their genomes with 824 eukaryotic genomes

Between 4 and 358 non-redundant HGTs per species were found in the genomes of 13 model organisms, and most of these HGTs were previously unknown

The majority of the 824 eukaryotes with full length genome sequences also contain HGTs.

These HGTs have transformed their host genomes with thousands of copies and have impacted hundreds, even thousands of genes.

Our findings revealed that HGTs are widespread in eukaryotic genomes, and HGT is a ubiquitous driver of genome evolution for eukaryotes.

Comments

Post a Comment

Popular posts from this blog

Beyond the Sequence: The Epigenetic "Fingers" That Play the DNA Keyboard

Image
Imagine the keyboard itself is not a standard piano keyboard, but a modular synthesizer, capable of producing an almost infinite array of sounds. The DNA sequence, then, represents the fundamental building blocks of this synthesizer, the raw materials from which all sounds are generated. Epigenetics, our "fingers," manipulates these building blocks, adjusting parameters like volume, timbre, and rhythm, transforming the raw potential of the DNA sequence into a symphony of cellular functions. We can further refine the "fingers" analogy. Consider that each finger represents a distinct epigenetic mechanism: DNA methylation, histone modifications, and non-coding RNA.  DNA methylation, for instance, might be the "index finger," capable of precisely silencing specific genes, like muting individual keys on the synthesizer. Histone modifications, the "middle finger," could represent the ability to adjust the accessibility of the DN...
Read more

Why are Christian philosophers running towards Darwin while biologists are "running" away?

Image
As nature reveals the strength of epigenetics and the weakness of Neo-Darwinism, biologists are “running” away from the long-standing accepted theory. In The Federalist , April 2019, Benjamin Dierker reviews “Why one-third of biologists now question Darwinism”: "Current estimates are that approximately one-third of professional academic biologists who do not believe in intelligent design find Darwin’s Theory inadequate to describe all of the complexity in biology.” Dierker continues, “The important note is that these are not ideologues or religious zealots, nor do they propose a god or biblical solution.  Rather, they find problems in the lack of explanatory power of Darwin’s theory in light of modern understanding of mutation, variation, DNA sequencing and more. These expressions of doubt do not reject naturalism or evolution per se, but the rigor of the Neo-Darwinian model for explaining the development of life.” For 40 years, scientists calculated natural se...
Read more

Rewriting the Rules: Epigenomic Mutation Bias Challenges Randomness in Evolution

Image
This research challenges the long-held dogma that mutations occur randomly, irrespective of their consequences, by demonstrating a clear, epigenome-mediated mutation bias in Arabidopsis thaliana . The study meticulously unveils how mutation rates are not uniform across the genome but are significantly reduced in functionally constrained regions, particularly within gene bodies and essential genes. This discovery fundamentally alters our understanding of evolutionary processes, suggesting that mutation is not a purely directionless force. "Mutation bias reflects natural selection in Arabidopsis thaliana" This opening statement encapsulates the core finding: mutation rates are not random but reflect epigenetic pressures. The authors demonstrate that mutations are less frequent in crucial genomic regions, directly contradicting the prevailing theory of random mutation. This observation suggests an active mechanism that minimizes deleterious mutations in essentia...
Read more